title: Heteroleptic copper(I) complexes prepared from phenanthroline and bis-phosphine ligands.
abstract: Preparation of [Cu(NN)(PP)](+) derivatives has been systematically investigated starting from two libraries of phenanthroline (NN) derivatives and bis-phosphine (PP) ligands, namely, (A) 1,10-phenanthroline (phen), neocuproine (2,9-dimethyl-1,10-phenanthroline, dmp), bathophenanthroline (4,7-diphenyl-1,10-phenanthroline, Bphen), 2,9-diphenethyl-1,10-phenanthroline (dpep), and 2,9-diphenyl-1,10-phenanthroline (dpp); (B) bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)benzene (dppb), 1,1'-bis(diphenylphosphino)ferrocene (dppFc), and bis[(2-diphenylphosphino)phenyl] ether (POP). Whatever the bis-phosphine ligand, stable heteroleptic [Cu(NN)(PP)](+) complexes are obtained from the 2,9-unsubstituted-1,10-phenanthroline ligands (phen and Bphen). By contrast, heteroleptic complexes obtained from dmp and dpep are stable in the solid state, but a dynamic ligand exchange reaction is systematically observed in solution, and the homoleptic/heteroleptic ratio is highly dependent on the bis-phosphine ligand. Detailed analysis revealed that the dynamic equilibrium resulting from ligand exchange reactions is mainly influenced by the relative thermodynamic stability of the different possible complexes. Finally, in the case of dpp, only homoleptic complexes were obtained whatever the bis-phosphine ligand. Obviously, steric effects resulting from the presence of the bulky phenyl rings on the dpp ligand destabilize the heteroleptic [Cu(NN)(PP)](+) complexes. In addition to the remarkable thermodynamic stability of [Cu(dpp)2]BF4, this negative steric effect drives the dynamic complexation scenario toward almost exclusive formation of homoleptic [Cu(NN)2](+) and [Cu(PP)2](+) complexes. This work provides the definitive rationalization of the stability of [Cu(NN)(PP)](+) complexes, marking the way for future developments in this field.
authors.affiliation: Laboratoire de Chimie des Matériaux Moléculaires, Université de Strasbourg et CNRS (UMR 7509) , 25 rue Becquerel, 67087 Strasbourg Cedex 2, France.
authors.forename: Adrien
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authors.forename: Meera
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authors.lastname: Mohankumar
authors.forename: John
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authors.forename: Filippo
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authors.forename: Michel
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authors.forename: Juan-José
authors.initials: JJ
authors.lastname: Cid
authors.forename: Omar
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authors.lastname: Moudam
authors.forename: Iwona
authors.initials: I
authors.lastname: Nierengarten
authors.forename: Lydia
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authors.lastname: Karmazin-Brelot
authors.forename: Carine
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authors.lastname: Duhayon
authors.forename: Béatrice
authors.initials: B
authors.lastname: Delavaux-Nicot
authors.forename: Nicola
authors.initials: N
authors.lastname: Armaroli
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Nierengarten